Rig telemetry system

ABSTRACT

A drillstring communications system includes one or more pipe segments, a communication sub coupled to the pipe segment that includes a communication sub antenna, and a leaky feeder antenna in communication with the communication sub antenna.

BACKGROUND

Exploration and production of hydrocarbons generally requires that aborehole be drilled deep into the earth. The borehole provides access toa geologic formation that may contain a reservoir of oil or gas.

Drilling operations require many resources such as a drilling rig, adrilling crew, and support services. These resources can be veryexpensive. In addition, the expense can be even much higher if thedrilling operations are conducted offshore. Thus, there is an incentiveto contain expenses by drilling the borehole efficiently.

Efficiency can be measured in different ways. In one way, efficiency ismeasured by how fast the borehole can be drilled. Drilling the boreholetoo fast, though, can lead to problems. If drilling the borehole at ahigh rate-of-penetration results in a high probability of damagingequipment, then resources may be wasted in downtime and repairs. Inaddition, attempts at drilling the borehole too fast can lead toabnormal drilling events that can slow the drilling process.

There are many types of problems that can develop during drilling suchas whirl and stick-slip. Stick-slip relates to the binding and releaseof the drill string while drilling and results in torsional oscillationof the drill string. Stick-slip can lead to damage to the drill bit and,in some cases, to failure of the drill string.

One way to transfer actual conditions from a downhole location to thesurface is to utilize mud-pulse telemetry. Mud-pulse telemetry is acommon method of data transmission used by measurement while drillingtools. Such tools typically include a valve operated to restrict theflow of the drilling mud (slurry) according to the digital informationto be transmitted. This creates pressure fluctuations representing theinformation. The pressure fluctuations propagate within the drillingfluid towards the surface where they are received by pressure sensors.Another way to transfer information may be to utilize an electromagnetic(EM) telemetry system.

In some cases, however, the bandwidth of EM and mudpulse telemetrysystems may not be sufficient to provide all of the data required by themodels in a timely manner. In some cases a wired pipe is utilizedinstead as a telemetry system.

SUMMARY

According to one embodiment, a drillstring communications system thatincludes one or more pipe segments, a communication sub coupled to thepipe segment that includes a communication sub antenna, and a leakyfeeder antenna in communication with the communication sub antenna isdisclosed.

In another embodiment, a method of communicating information between adownhole location and a surface computing device that includes:transmitting a signal from the downhole location through telemetrysystem to a surface sub; transmitting the signal or a signal formed fromthe signal wirelessly from the surface sub; and receiving the signal ora signal formed from the signal with a leaky feeder antenna isdisclosed.

In another embodiment, a drill string communications system thatincludes one or more drill pipe segments; a communication sub coupled tothe drill pipe segment that includes a communication sub antenna; and aplurality of leaky feeder antennas in communication with thecommunication sub antenna is disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alikein the several Figures:

FIG. 1 is a schematic diagram showing a drilling rig engaged in drillingoperations;

FIG. 2 is a simplified version of rig showing a system according to oneembodiment; and

FIG. 3 shows a cut-away perspective view of a leaky feed antenna.

DETAILED DESCRIPTION

As mentioned above, while drilling, it is desired to stay in constantcommunication with the downhole equipment. While drilling or trippingdownhole equipment (e.g. drill pipes) in or out, the elevator ortopdrive is moving up and down and drillstring components. During suchtimes it may be beneficial to provide communication from the telemetrysystem of the drill string to an computing device. According to oneembodiment, a wireless communication systems are desired, such as a widearea local area network (WLAN) is provided that allows for communicationwhile drill pipes are being added. The WLAN sender and receiver may bearranged such that a good transmission of data is possible at eachposition of the rig. This is challenging, as the rig tower is typicallybuild of steel. It shall be understood, that other wireless standardsand frequencies as e.g. blue tooth could also be used.

Connection issues could be solved by installing a leaky feeder verticalalong at least part of the rig tower at or near the derrick. As usedherein, “vertical” means more than 45° from horizontal. The oppositesender/receiver could be rotated or non-rotated with the drill string.It is also possible to route a leaky feeder around the surface sub toget sender and receiver adverse in each rotational position of thesurface sub. One possible advantage of using a leaky feeder is thatreliable communication to the downhole equipment is possible at thesurface, but no wires have to be moved up and down the rig whiledrilling or tripping. This is of interest especially for wired pipetelemetry, as the data rate is much higher than with other telemetrysystems like mud pulse or EM (electromagnetic) telemetry. With aconstant communication to the downhole tools, it may be possible todetect kicks, stick slip and other dangerous situations and reactinstantly.

FIG. 1 is a schematic diagram showing a drilling rig 1 engaged indrilling operations. Drilling fluid 31, also called drilling mud, iscirculated by pump 12 through the drill string 9 down through the bottomhole assembly (BHA) 10, through the drill bit 11 and back to the surfacethrough the annulus 15 between the drill string 9 and the borehole wall16. The BHA 10 may comprise any of a number of sensor modules 17, 20, 22which may include formation evaluation sensors and directional sensors.The sensor modules 17, 20, 22 and can measure information about any of,for example, the tension or stain experienced by the drill string,temperature, pressure, and the like.

While not illustrated, it shall be understood that the drilling rig 1can include a drill string motivator coupled to the drill string 9 thatcauses the drill string 9 to bore in into the earth. The term “drillstring motivator” relates to an apparatus or system that is used tooperate the drill string 9. Non-limiting examples of a drill stringmotivator include a “lift system” for supporting the drill string 9, a“rotary device” for rotating the drill string 9, a “mud pump” forpumping drilling mud through the drill string 9, an “active vibrationcontrol device” for limiting vibration of the drill string 9, and a“flow diverter device” for diverting a flow of mud internal to the drillstring 9. The term “weight on bit” relates to the force imposed on theBHA 10. Weight on bit includes a weight of the drill string and anamount of force caused by the flow of mud impacting the BHA 10.

The BHA 10 also contains a communication device 19 that, in oneembodiment, can induce pressure fluctuations in the drilling fluid 31 orintroduce electromagnetic pulses into the drill string 9. The pressurefluctuations, or pulses, propagate to the surface through the drillingfluid 31 or the drill string 9, respectively and are detected at thesurface by a sensor 18 and conveyed to a control unit 24. The sensor 18is connected to the flow line 13 and may be a pressure transducer, oralternatively, may be a flow transducer. In another embodiment thecommunication device 19 may provide electrical signals that are carriedby a wired pipe telemetry system to the surface.

In one embodiment, the control unit 24 may include programming or othermeans of storing models of physical characteristics of the drill string9. For example, in one embodiment, the control unit 24 includes one ormore models that model torsional oscillations in the drill string 9.

In one embodiment, the communication device 19 received data from thesensor modules 17, 20, 22 and provides that information to the controlunit 24 fast enough to effectively determine the model parameters.

According an embodiment of the present invention, the BHA 10 includes aprocessor 21.

FIG. 1 also includes a plurality of leaky feeder antennas 25. Only oneantenna is required and the lengths can vary as shown by the differencesin antennas 25 a and 25 b.

As mentioned above, it may be desirable for the drilling crew to haveaccess to the downhole information while drilling, tripping or addingpipe. Tripping may be necessary for a number of well operationsinvolving a change to the configuration of the bottom-hole assembly,such as replacing the bit, adding a mud motor, or adding measurementwhile drilling (MWD) or logging while drilling (LWD) tools. Tripping cantake many hours, depending on the depth to which drilling hasprogressed. The ability to maintain communication with downhole toolsand instruments during tripping (or even adding pipe) can enable a widevariety of MWD and LWD measurements to be performed during time thatotherwise would be wasted. !Maintaining communication during trippingmay also give timely warning of lost circulation or of other potentialproblems, thereby enabling timely corrective action. It is also possibleto transmit data while drilling or at least turning the drillstring,without an extra transfer from the rotating part to a non-rotating parton the rig. With regards to safety is also beneficial, as there is noconnector for a data cable that could be a risk for an ignition sourcein an explosive atmosphere.

According to one embodiment, an adapter sub is provided that convertssignals received at a top pipe segment into a radio frequency signal.This signal is received by leaky feeder antenna 25 and provided to, forexample, control unit 24 (or other computing device) for furtherprocessing. The adapter sub 30 is best shown in FIG. 2 and shall beunderstood as being attached to the top 8 or one of the top segments ofdrill pipe. The adapter sub 30 may be connected to the swivel 27 oranother such device.

With reference to FIGS. 1 and 2, as the swivel 27, and consequently, sub30 and pipe segment 8 move up and down (as indicated by arrow 36), thelocation of the sub 30 is moving relative the rig 1. Providing a leakyfeeder antenna 25 on the rig 1 allows for the signal to be received fromthe sub 30 regardless of its location. The sub 30 may include aconverter 34 and an antenna 32. The antenna 32 provides signals to andreceives signals from the leaky feeder antenna 25. The converter 34converts a signal received by the antenna 32 into a format fortransmission though pipe segment 8 (e.g., it may convert this signalinto a signal used in a wire pipe transmission system) and vice versa.

FIG. 3 shows an example of a leaky feeder antenna 25. The leaky feeder25 may be formed from a coaxial cable 40 having an inner conductor 48surrounded by dielectric 46 and shielding 44. Small sections of smallsections 42 of its shielding 44 are stripped away to allow radiofrequency (RF) signals to escape/enter. Leaky feeders, which act asextended antennas and may also be called radiating cables.

In support of the teachings herein, various analysis components may beused, including digital and/or an analog systems. For example, thecontroller unit 24 and the processor 21 can include digital or analogsystems. The system may have components such as a processor, storagemedia, memory, input, output, communications link (wired, wireless,optical or other), user interfaces, software programs, signal processors(digital or analog) and other such components (such as resistors,capacitors, inductors and others) to provide for operation and analysesof the apparatus and methods disclosed herein in any of several mannerswell-appreciated in the art. It is considered that these teachings maybe, but need not be, implemented in conjunction with a set of computerexecutable instructions stored on a computer readable medium, includingmemory (ROMs, RAMs), optical (CD-ROMs), or magnetic (disks, harddrives), or any other type that when executed causes a computer toimplement the method of the present invention. These instructions mayprovide for equipment operation, control, data collection and analysisand other functions deemed relevant by a system designer, operator,owner, user or other such personnel, in addition to the functionsdescribed in this disclosure.

Further, various other components may be included and called upon forproviding for aspects of the teachings herein. For example, a powersupply (e.g., at least one of a generator, a remote supply and abattery), vacuum supply, pressure supply, cooling component, heatingcomponent, motive force (such as a translational force, propulsionalforce or a rotational force), magnet, electromagnet, sensor, electrode,transmitter, receiver, transceiver, antenna, controller, optical unit,mechanical unit (such as a shock absorber, vibration absorber, orhydraulic thruster), electrical unit or electromechanical unit may beincluded in support of the various aspects discussed herein or insupport of other functions beyond this disclosure.

Elements of the embodiments have been introduced with either thearticles “a” or “an.” The articles are intended to mean that there areone or more of the elements. The terms “including” and “having” areintended to be inclusive such that there may be additional elementsother than the elements listed. The term “or” when used with a list ofat least two elements is intended to mean any element or combination ofelements.

It will be recognized that the various components or technologies mayprovide certain necessary or beneficial functionality or features.Accordingly, these functions and features as may be needed in support ofthe appended claims and variations thereof, are recognized as beinginherently included as a part of the teachings herein and a part of theinvention disclosed.

While the invention has been described with reference to exemplaryembodiments, it will be understood that various changes may be made andequivalents may be substituted for elements thereof without departingfrom the scope of the invention. In addition, many modifications will beappreciated to adapt a particular instrument, situation or material tothe teachings of the invention without departing from the essentialscope thereof. Therefore, it is intended that the invention not belimited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims.

1. A drillstring communications system, the system including: one ormore pipe segments; a communication sub coupled to the pipe segment thatincludes a communication sub antenna; and a leaky feeder antenna incommunication with the communication sub antenna.
 2. The system of claim1, wherein the leaky feeder antenna is arranged vertically.
 3. Thesystem of claim 1, further comprising: a drilling rig; wherein the leakyfeeder antenna is physically attached to the drilling rig.
 4. The systemof claim 3, wherein the leaky feeder antenna is arranged vertically. 5.A method of communicating information between a downhole location and asurface computing device comprising: transmitting a signal from thedownhole location through telemetry system to a surface sub;transmitting the signal or a signal formed from the signal wirelesslyfrom the surface sub; and receiving the signal or a signal formed fromthe signal with a leaky feeder antenna.
 6. The method of claim 5,wherein the leaky feeder antenna is arranged vertically.
 7. The methodof claim 5, wherein the leaky feeder antenna is attached to a drillingrig.
 8. The method of claim 7, wherein the leaky feeder antenna isarranged vertically.
 9. A drill string communications system, the systemincluding: one or more drill pipe segments; a communication sub coupledto the drill pipe segment that includes a communication sub antenna; anda plurality of leaky feeder antennas in communication with thecommunication sub antenna.
 10. The system of claim 9, wherein the leakyfeeder antennas are arranged vertically.
 11. The system of claim 10,further comprising: a drilling rig; wherein the leaky feeder antennasare physically connected to the drilling rig.
 12. The system of claim11, wherein the leaky feeder antennas are arranged vertically.
 13. Thesystem of claim 9, wherein the drill pipe segments are wired pipesegments.
 14. The system of claim 1, wherein the drill pipe segments arewired pipe segments.